A multimedia system provides end-to-end service delivery by bundling high speed multimedia streams for transmission over ATM or other networks, unbundling them and using or storing them. Such streams may correspond to video, audio, signals used to control robotic applications, force-feedback applications, agile manufacturing and the like. A typical application may correspond to transmitting video and audio signals over an ATM network to a desired endpoint. The video signals may emanate as a digitized file from a file server or be an external analog video signal as from a camera, laser disc or VCR which must be digitized, compressed and then sent to a network interface (NIC) card for transmission into digital network for eventual reception by another multimedia terminal that would perform the inverse operation of demultiplexing, decoding and sending the decoded video signal to an analog television monitor.
Multimedia signals are typically high-bandwidth and time-sensitive in nature. A suitable compression scheme is, therefore, required such as MPEG-2 (Motion Picture Experts Group) and involves bit-rates in excess of 4 Megabits per second up to as high as 20 Megabits per second. One of the problems when faced with such high bandwidth signals is how to build an inexpensive high-bandwidth multiplexer to packetize and synchronize multiple media streams into one multiplex stream.
Another problem involves multimedia signals that transfer video data. The compressed video frame sizes vary significantly and the instantaneous bit-rate can be quite bursty especially during scene-changes in the source resulting in the overflow of the FIFO.
Accordingly, it is an object of the present invention to provide a multiplexer which utilizes an improved circuit to control overflow of data into the FIFO.